9D-USTE Geometric Origin of Quantum Phenomena: Double-Slit Interference from 6D Internal Field Fluctuations

In this work, we extend the 9-dimensional Ultra-Spacetime-Time-Evolution (9D-USTE) framework to explain the origin of quantum double-slit interference from pure geometric field dynamics. Based on the 3+6 dimensional spacetime structure (3D macroscopic spacetime plus a compact 6D internal manifold), a scalar field σ (radion field) governing the volume of the 6D compact internal manifold is shown to exhibit wave-like propagation across the entire spatial region, while the corresponding particle is localized in 3D macroscopic space. We demonstrate that the observed interference pattern is directly identified with the squared gradient of the σ field, whose fluctuations pass through both slits and superimpose. The particle trajectory is guided by the geometric field distribution, yielding a fully deterministic geometric interpretation of quantum duality without wavefunction collapse, nonlocality, or probabilistic postulates. Quantitative estimates of the σ field mass m_σ are provided, and the correspondence between the σ-field wavelength and the de Broglie wavelength is established by fitting existing electron and C₆₀ double-slit experimental data. We further discuss how the compact 6D internal manifold provides a geometric mechanism to address Bell inequality-related nonlocality concerns, distinguishing the 9D-USTE framework from existing Bohmian mechanics and Kaluza-Klein theories. This work advances 9D-USTE as a consistent geometric alternative for unifying classical gravity and quantum phenomena.